Due to the fast progress of material technology of permanent magnet, a small NdFeB permanent magnet with diameter 60 mm can attract up a steel plate with 1000 kilogram.
Conventional stirring mechanism includes a simple mechanical motion for stirring without using the attractive and repulsive force of the permanent magnet.
U.S. Pat. No. 7,520,657 discloses a magnetic stirring system that includes a stir-mantle and a magnetic stirring apparatus used for stirring/mixing materials in a flask. A rare-earth magnet is mounted on the magnetic stirring apparatus and is driven in rotation by a pneumatic motor. The rare-earth magnet is coupled to a magnetic stir bar in the flask for joint rotation so that the stir-bar stirs/mixes the materials in the flask. An exhaust is included to channel air from the motor to the rare-earth magnet and to direct the air to flow over the magnet to control the temperature of the magnet.